Stefanos Tsitsipas has defeated Dominic Thiem, who he first met at this tournament in 2016, to win the ATP Finals in London.

Stefanos Tsitsipas walked into the interview room and the huge silver cup, the Brad Drewett Cup, was placed alongside him and his big smile got even bigger as he moved his long hair out of his face. It was to get a better look at the trophy.

I asked him if he could believe it, if he was able to put into words how extraordinary the week had been, how wonderful the year was starting with his win over Roger Federer at the Australian Open; if he was able to describe his excitement.

He inhaled enough oxygen for three people it seemed, and his face lit up once again.

“I'm really excited to -- firstly, I was excited to be part of the Nitto Finals experience,” he said. “For me, it was already a big thing. Now that I'm a champion, I don't know how to explain it. I honestly don't feel anything, because it's too many emotions to feel something. So, it's horrific, in a way, to be holding this trophy.

“I remember myself watching this event on TV and thinking, oh, these guys have done an insane year to be playing here. And now I'm in the position to be champion, so it feels awesome.”

In two hours 35 minutes Mr. Tsitsipas was champion in match that could have gone either way. He defeated Dominic Thiem 6-7, 6-2, 7-6. Both players were striking the ball superbly and it was quite a sight having two singles handed backhands squaring in such a big final. 

Mr. Tsitsipas was working hard to keep pressure on the Austrian was saving break points and then went on to win a very tight tiebreak 8/6. The fact that it was tight and tense many would have been considering that Mr. Thiem would run away with the final, that the Greek might have felt deflated. Instead it was quite the opposite as Mr. Tsitsipas went up a double break, led 4-0 and 5-1. Mr. Thiem picked up one more game before the set was settled.

The 21-year-old Greek once again opened up the advantage; he was up 3-1 before the Austrian levelled and they continued on serve to the tiebreak. The advantage swayed but then Stefanos produced great returns to close it out, the final point being a forehand from Mr. Thiem that floated out.

“Especially third-set tiebreak in championship match is always about being lucky, about being unlucky. It's always, I would say, 50/50,” Mr. Thiem said. “I missed some very close balls in the tiebreak, which against Novak or which in other matches in the last weeks went in. That was the thing in the third-set tiebreak.

“But, you know, I cannot do anything now about it. It was a great match from both of us, and he really deserves that win. I mean, actually, we both deserve it, but there is only one winner in tennis. So that's it. I'm happy also with this match today.

“In general, I'm pretty happy with my game and with my season, especially from after the US Open. It's a big, big disappointment right now, but at the end it was, I would say, 90% positive this season.”

Stefanos dropped to his knees and he hit the court hard enough that his right knee was bleeding but he didn’t care, and he did not feel anything. He is the youngest champion of this event since 2001 and it’s the fourth year in a row there has been a new name on the winner’s trophy, the last time that happened was 1988 to 1991.